Project Summary Sport-related concussions are a serious public health concern in the United States, with 1.6 to 3.8 million concussions reported annually. Young athletes who suffer a concussion experience quality of life alterations, with cognitive impairment, reduction in balance or coordination, and memory loss. Unfortunately, several factors limit the ability to accurately and feasibly evaluate the deleterious effects resulting from a concussion. First, current concussion assessment guidelines are consensus, not evidence based, resulting in variable practice patterns that often rely on subjective measurements. Second, impairments in neurological function are difficult to quantify using currently available testing techniques, leading to potential misdiagnosis or early clearance for return to play or school. Finally, though gait evaluations are recommended as part of a thorough neurological examination following a concussion, financial, time, and personnel limitations prohibit the use of instrumented gait testing in most sports medicine and athletic training clinical environments. Therefore, the long-term objective of this project is to address these limitations related to routine concussion evaluations through the use of smartphone-based cognitive and gait assessments to facilitate efficient concussion management. Gait analysis can not only be used to reveal overall health status, but is also beneficial in assessing abnormal ambulation, quantifying disease progression and prognosis, measuring treatment effectiveness, predicting injury risk, and informing return-to-play. Furthermore, investigating dual-task gait function highlights the demanding nature of sports, where athletes must quickly react to stimuli by balancing gait and cognitive demands. With the ubiquity of smartphones, and the availability of numerous embedded sensors, walking performance metrics can be easily and accurately measured. Recently, we have demonstrated the reliability and validity of a smartphone-based accelerometer in quantifying spatiotemporal gait parameters (gait velocity, cadence, step length, step time) when attached to the body or in a bag, belt, hand, or pocket during comfortable, slow, and fast speeds. In addition, we have validated smartphone-based gait measures among healthy athletes in single- and dual-task conditions. Therefore, this Phase I SBIR will result in the development of a novel smartphone application that can assess concurrent cognitive and gait performance in the free-living environment. The aims of this proposal are to 1) Develop a clinical tool to evaluate single- and dual-task gait and cognitive function in an automated fashion among high school athletes using a smartphone; and 2) Determine the reliability and sensitivity of this tool across time in a cohort of concussed and uninjured high school athletes. The ultimate goal of this project is to establish an objective, easy-to-use, low-cost instrument for evaluating concussed athletes in order to monitor recovery, guide return-to play decisions, and reduce future injury.